Mass accelerator



April 23, 1963 TSENG w. LIAO 3,086,424

MASS ACCELERATOR Filed July 1a, 1956 VOL TA GE VOL TA 65 VOL TA SOURCE SOURCE SOURCE Ir? verv t or Ts ervg 14/. L iao,

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ilnited rates Patent 3,086,424 MASS ACCELERATGR Tseug W. Lian, Pittsfield, Mass, assignor to General Electric Company, a corporation of New York Filed July 18, 195s, Ser. No. 598,678 4 (Ilairns. (Cl. 89-8) This invention generally relates to improvements in means for generating and applying electrical energy to propagate a mass down the length of an enclosure at great speed.

In a prior application of Yusuf A. Yoler, Serial No. 570,001, filed March 7, 1956, now Patent 2,733,684, assigned to the same rassignee, there is disclosed a method and apparatus for successively discharging electrical energy, by a plurality of electrical arcs, into an enclosure immediately behind a moving projectile or behind a traveling shock wave in such a controllable manner and in such sequence that the projectile or shock wave is driven down the length of the enclosure at a uniformly high acceleration and progressively increases speed at a greater rate than could be previously obtained by lcnown guns or shock wave generating devices. More specifically in this arrangement, a series of spaced electrical arc discharges are initiated in sequence down the length of an enclosure behind the moving mass serving to greatly heat and expand the gases initially within the enclosure to perform the work of propagating the mass.

In accordance with the present invention, there is provided a unique means for enhancing the current density or ionization density in these electrical arc-s thereby to obtain a greater gas temperature and pressure for performing the work of propagating the mass.

It is accordingly one object of the present invention to provide an apparatus for efiiciently converting electrical energy to a form usable to propel a shock wave or a projectile down the length of an enclosure at great speed.

Other objects and many attendant advantages of this invention will be more readily comprehended to those skilled in this art upon a detailed consideration of the following specification taken with the accompanying drawing illustrating in side elevational view, partially in section, one preferred embodiment of the present invention.

For an understanding of the present invention, a brief description of the invention of said prior application shall be given with reference to FIG. 1 and thereafter the changes innovated by the present invention shall be described.

In said prior application, there is disclosed an elongate hollow tubular member, generally designated 10, that is sealed at the left-hand portion thereof and open ended at the right. A series of spaced conducting electrodes 13-15, inclusive, electrically insulated from one another by tube 10, are fixedly distributed along the length of this tubular member and an additional starter electrode 12 or fuse (not shown) is positioned to seal the left-hand portion of tube 10, as shown. Energizing each adjoining pair of these electrodes 12-15, inclusive, is a separate high voltage source of electrical energy 16-18, inclusive, with each source having its terminals energizing adjacent electrodes through an inductor 19 or other suitable electrical network for controlling the time constant of any electrical are that may discharge through that electrode.

The starting voltage source 16 energizing the end electrode 12 and the first electrode 13 through a normally open switch 20, is of large enough voltage to initiate an arc discharge through the gas, such as air or helium, with in the tube when this switch is closed. However, the potentials across the remaining electrodes 1315, inclusive, are not suificiently large to generate arcs within the tube.

Patented Apr. 23, 1963 Within tube 10, there is positioned a suitably formed projectile 21 that is adapted to be propelled with great speed as hereinafter described.

In operation, switch 20 is closed connecting electrical source 16 across end electrode 12 and first electrode 13. This high voltage generates an are within the tube across these electrodes; importing or dumping great heat and electrical energy into the tube and greatly pressurizing the gases within the tube. Concurrently, the electrical energy and the rapid heating of the vapor causes this gas to ionize. This heat and pressure propels projectile 21 in a direction down the length of the tube; and as this projectile moves down the tube, the ionized gas behind it travels between the first pair of electrodes 13 and 14-, lowering the electrical resistance of the gas between these electrodes and enabling a second arc to be generated there- :across. The second are feeds additional electrical energy into the tube at a position spaced from the first electrical discharge; and the second electrical discharge also greatly heats and pressurizes the gas within the tube. Thereafter as projectile 21 passes each pair of electrodes, the ionized gas continually moving behind, comes in contact with each successive pair of electrodes, lowering the resistance of the gas therebetween and permitting the associated voltage source interconnecting these adjoining electrodes to discharge an arc, thereby resulting in a successive series of arcs down the length of the tube immediately behind the projectile in such a manner as to maintain the energy content as a uniformly high predetermined level and result in the desired great speed of propagation of projectile 21 down the tube 10.

According to the present invention, there is provided a means for increasing the current or ionization density of these electrical discharges to provide higher gas temperatures and pressures and thereby greatly enhance the operation of this mass accelerator. This is preferably accomplished by lining the inside of the tube 10 with a radioactive material 22 such as tritium or polonium to provide greater primary ionization throughout the tube in readiness to be triggered, thereby increasing the ionization density when the discharge between the electrodes takes place.

Although the ionization density generated by such radioactive materials is small as compared to the ionization during the electrical are between the electrodes, the employment of radioactive materials increases the primary ionization to provide more intense arc discharges ionization in a manner somewhat analogous to the phenomena of the self-maintained glow in arc discharges that passes over into an arc. For example, as known to those skilled in the art, electrical discharges are initiated from free electrons in the vicinity of the primary ionization area, which are released by the occasional cosmic rays are non-uniformly oriented and therefore provide primary energization that is weak and non-uniformly spaced through the tube. By providing a coating or liner of radioactive material 22 throughout the tube, the primary ionization is uniformly distributed Within the tube whereby once the external electrical energy is applied to the ring electrodes a higher density discharge takes place between the ring electrodes.

Increasing the density of ionization between each of these electrodes increases the working temperatures and pressures serving to propagate the projectile down the tube, thereby propagating the projectile at greater speed and in a more efiicient manner down the length of the tube, as desired.

The material tritium is preferred as a liner since its range of ionization is about one-half of a centimeter, and if employed with a tube of about one-half inch diameter, this range is substantially equal to the radius of the bore of the tube. Consequently if tritium is employed as a layer about the inner wall, the ionization fills the entire tube and provides the highest degree of ionization along the center line of the tube. Additionally, properly selecting the concentration of tritium used in the space inter-mediate the first electrode 13 and the end electrode 12, the initial starting arc may be obtained with a relatively low voltage source 16.

Furthermore, since the radioactive material tritium is an isotope of hydrogen, the high temperatures generated by the arc discharges serve to release hydrogen from the tritium in such a manner as to increase the gas pressure within the tube. During the arcing, therefore, the gas pressure inside of tube 10 rises to extremely high values resulting from the evolution of gases from the tritium as well as from the great heating and pressurizing of the original gases within the tube from the arc itself.

Additionally, the cost of tritium material is relatively low, being, at present, about 10 per millicun'e, and the radiation hazard is slight since tritium emits beta rays of only .018 mev., necessitating only a pair of thin rubber gloves in handling this material.

Alternatively, the material polonium may also be used, when preferably combined with a gas composed of .1% of argon or hydrogen by weight in a helium mixture for the purpose of increasing its ionization up to 40 Polonium, however, is presently about 14 times as expensive as tritium.

Thus lining the tube 10 with radioactive materials in accordance with the present invention enables a more uniform and higher density of ionization to be obtained during each of the successive arc discharges, increasing the working temperature and thereby serving to prop-agate the mass at greater accelerations than before. Additionally, since the preferred tritium material discussed above releases quantities of hydrogen gas when subjected to the high temperatures of electrical arcs, this lining serves to additionally increase the gas pressure within the tube.

Although the preferred apparatus is illustrated in connection with the firing of a projectile down a tube, it is equally well suited to the propagation of a traveling shock wave as is more fully disclosed in the above-mentioned copending application.

It is believed well known to those skilled in the art that electrical arc discharges result in a considerably more effective propagating force than do the usual chemically generated reactions, since greater temperatures, more uniform heating, and greater control of the release of energy can be obtained than with the usual chemical reactions. It is further evidentto those skilled in the art that this means for generating and applying great useable energy can be obtained automatically or in a self-triggering manner that is quite simple and inexpensive since the movement of the propagated element or shock wave, itself, controls the switching of the various energy generating means to release energy within the tube in a desired set quence, thereby requiring no additional switching or timing mechanism. Additionally, if desired, more elaborate external circuitry may be employed to trigger the arc discharges in a different sequence or provide greater control of the time constants.

Although but one preferred apparatus has been disclosed and illustrated as required by the patent laws, it is believed evident to those skilled in the art that many changes may be made in the structure and arrangement of the tube, electrode, voltage sources, lining material or arrangement as well as in the other preferred details shown and described above without departing from the spirit and scope of this invention. For example, it is evident that many of the radioactive materials other than those mentioned above may be used with greater or lesser success depending upon the degree of ionization, the radiation hazard, the difiiculty of applying the materials, and whether or not light-weight gases are generated in the presence of the high temperature electric arcs. Since these and other changes are believed apparent to those skilled in the art upon a consideration of the above invention, this invention is to be considered as being limited only in accordance with the following claims appended hereto.

What is claimed is:

1. In an accelerator for propagating a mass by the successive discharge of electrical arcs down the length of an enclosure immediately behind said mass, means for increasing the current and ionization density of the arcs, said meansincluding a radioactive material lining the inner wall of said enclosure.

2. In a mass accelerator for propagating a mass by the successive discharge of electrical arcs down the length of an enclosure immediately behind said mass, means for increasing the uniformity and ionization density of the arcs, said means including a layer of radioactive material formed inside of said enclosure member, said radioactive material selected from the class consisting of tritium and polonium.

3. A mass accelerator comprising an elongated hollow tubular member having a lining, said member having one end sealed and one end open, a plurality of electrodes in said member, said electrodes being spaced along the length of the member and electrically insulated from one another, a projectile adapted to be placed in the tubular member with a low atomic weight gas confined bet-ween the projectile and the sealed end of the member, said lining including a radioactive material selected from the class consisting of tritium and polonium and means for connecting a source of electrical power to said electrodes.

4. In the device of claim 3 in which the gas is formed of helium and a small percentage by weight of a gas selected from the class consisting of hydrogen and argon.

References Cited in the file of this patent UNITED STATES PATENTS 2,783,684 Yoler Mar. 5, 1957 

2. IN A MASS ACCELERATOR FOR PROPAGATING A MASS BY THE SUCCESSIVE DISCHARGE OF ELECTRICAL ARCS DOWN THE LENGTH OF AN ENCLOSURE IMMEDIATELY BEHIND SAID MASS, MEANS FOR INCREASING THE UNIFORMITY AND IONIZATION DENSITY OF THE ARCS SAID MEANS INCLUDING A LAYER OF RADIOACTIVE MATERIAL FORMED INSIDE OF SAID ENCLOSURE MEMBER, SAID RADIOACTIVE MATERIAL SELECTED FROM THE CLASS CONSISTING OF TRITIUM AND POLONIUM. 